1. Field of the Invention
The present invention relates to a scroll type compressor which is a coolant compressor used in a freezer or an air conditioner and is provided with a coil-like fixed scroll and an orbiting scroll that interlocks with the fixed scroll to form a scroll chamber, in which the volumetric capacity of the scroll chamber is varied with the orbiting motion of the orbiting scroll to compress the coolant.
2. Description of the Related Art
A scroll type compressor of the prior art is provided with a driving shaft that is rotated by a means for drive such as an electric motor, an orbiting scroll member which is mounted decentered (i.e. eccentrically) on the drive shaft and a fixed scroll member that interlocks with the orbiting scroll member to form a compression space (scroll chamber). The volumetric capacity of the scroll chamber is varied by orbiting the orbiting scroll member relative to the fixed scroll member to take in, compress and discharge the coolant. In this type of structure, the lubrication of the various sliding contact surfaces of the scroll type compressor is a crucial factor.
The scroll type compressor disclosed in Japanese Patent Unexamined Publication No. H3-149391 includes the main shaft oil groove 35 formed on an inclination on the external circumference of the main shaft 18 and in the surface where it slides in contact with the main bearing 19 as shown in FIGS. 2 through 4 of that publication. It also includes the swinging drive shaft oil groove 38 formed on an inclination on the external circumferential side surface of the swinging drive shaft 16 and on the surface where the decentered bearing 17 is in contact with the swinging drive shaft 16. An oil pump is mounted to this configuration. The main shaft oil groove 35 and the swinging drive shaft oil groove 38 deliver lubricating oil supplied by the oil pump to the sliding contact surfaces with the rotation of the drive shaft and the swinging motion of the swinging drive shaft. After lubrication, the oil is discharged into the balance weight chamber 36.
Also, Japanese Unexamined Patent Publication No. H4-47185 discloses a compressor provided with the oil groove 17 formed on an inclination on the external circumferential surface of the crank shaft 4 where it is in sliding contact with the bearing 9a. With this compressor, lubricating oil supplied from the oil supply pipe 18 is taken in at the leading end of the oil groove 17 due to the rotation of the crank shaft 4 to lubricate the surface where it is in sliding contact with the bearing 9a.
In addition, Japanese Unexamined Patent Publication No. H4-203377 discloses a compressor provided with a circumferential groove 21 formed on the external circumferential surface of the crank shaft 9 where it is in sliding contact with the lower bearing 11. At least one oil groove 19 is formed on an inclination extending from the circumferential groove 21. Lubricating oil supplied through an oil supply port 20 formed in the crank shaft 9 travels upward through the oil groove 19 due to the rotation of the crank shaft 9 to lubricate the surface where it is in sliding contact with the lower bearing 11.
However, although a compressor in which lubricating oil is supplied through an oil groove (spiral groove) has a sufficient capacity for supplying lubricating oil during low speed rotation, a sufficient supply of lubricating oil cannot be ensured during high speed rotation because the oil induction port is located toward the outside from the spiral groove and thus, centrifugal force becomes a factor during high speed rotation.
The example disclosed in Japanese Unexamined Patent Publication No. H3-149391 described above, attempts to solve this problem by mounting an oil pump (volumetric capacity pump). However, this creates many problems such as increased number of parts, difficulties in machining, high production costs and the like.